Recently, demands on a small-sized compact camera module are on the increase for use in various multimedia fields including notebook type personal computers, camera phones, PDAs (Personal Digital Assistants), Smartphones and toys, and further in image input equipment including monitoring cameras and information terminals for video tape recorders.
Particularly, designs are elements that have a great influence on sales of mobile phones, whereby small-sized camera modules are greatly demanded.
The camera module is manufactured employing an image sensor or a photoelectric conversion device such as a CCD (Charge Coupled Apparatus) type or a CMOS (Complementary Metal Oxide Semiconductor) type to converge light from an object to a photosensitive element and to form an image of the object. That is, light of the object is concentrated by image sensor chips through a lens, an optical signal of the light is converted to an electric signal, and the image is transmitted to allow the object to be displayed on a display medium such as an LCD (Liquid Crystal Display) display device.
The camera module generally includes a plurality of lenses, and a driving source is mounted to each lens to move the lens and to change a relative distance thereof, whereby an optical focal length is adjusted.
FIG. 4 is a camera module according to prior art, which will be described briefly.
Referring to FIG. 4, an image sensor (2) is mounted on a printed circuit board (1, PCB), and a lens unit (3) disposed with a plurality of lenses is positioned at an upper surface of the image sensor (2) on a light irradiation path. Furthermore, a holder (4) for supporting the lens unit (3) and guiding positions is mounted.
The lens unit (3) in the conventional camera module is mounted at an upper periphery of the PCB (1) by an adhesive for the light to be irradiated to the image sensor (2) through the plurality of lenses. At this time, the adhesive is bonded, on the drawing, to a bottom surface of the lens unit (3) or to the upper periphery of the PCB (1) to allow the lens unit (3) to be bonded, where the following problems occur as conventional epoxy is coated as an adhesive to allow the lens unit (3) to be bonded.
In case the epoxy is coated for bonding, the coating must be conducted to form a relatively even surface, and if the relatively even surface is not formed, a vertical tilt is generated on the lens unit (3) to affect a resolution, whereby a physical influence is affected on the image sensor (2) nearby the PCB (1) to resultantly affect the resolution.
Furthermore, another problem is that adhesive power becomes weak due to narrowness of coated surface of epoxy, that is, narrowness of bonded surface, to decrease performance of the image sensor (2) as a result of heat or gas generated in the course of curing of the epoxy. Still another problem is that ghost phenomenon occurs due to the gas.